Salisbury's Conservative MP Robert Key says a failure to deliver long overdue improvements means Stonehenge no longer deserves the listing.

He claims money for improvements is being diverted to the Olympics.

He is writing to the UNESCO committee asking for the British government to be called to account.

Unique archaeology

"A plan is there which has been discussed endlessly but they've failed to make a decision," he said.

A £600m plan to drill a tunnel for the nearby A303 trunk road and build a major new visitor centre has been on review for more than a year after Transport Minister Stephen Ladyman said costs had risen too far.

But those campaigning to preserve the unique archaeology of the region say the plan is the only compromise that could work for the area.

TV archaeologist and Labour Party activist Tony Robinson said he was very worried about the future of Stonehenge.

Cultural legacy

In an interview with the BBC's Politics Show he accused the government of "leeching" on the iconic image of the monument to win the bid for the Olympics.

"As a nation we're in danger of letting Stonehenge down badly. Most politicians don't get heritage, they think they can just leech on it, exploit it, that it doesn't need tending," he said.

English Heritage, the government agency that runs Stonehenge, do not dispute visitor facilities and access are inadequate, but still hope improvements will be made in time for the Olympics.

"It is a stated aim of Visit Britain and the government to maximise the benefits of hosting the Olympics," a spokesman said.

He added that the Stonehenge project would be a major contribution to the cultural legacy of the games.